A variety of products, especially in medicine and food processing, require strict adherence to certain upper or lower temperature limits during their storage and transport. Otherwise, their characteristic properties are impaired or lost.
Monitoring systems suitable to guarantee such recording have already been developed with widespread use of so-called transition indicators. These transition indicators are in a position to record the adherence to certain value limits, for instance temperature. A further variation of these systems are the so-called data loggers, which are included with the goods to be monitored as electronic cubes or blocks of several cm.sup.3 volume.
A major draw-back of the transition indicators mentioned first is that they only discern the adherence to certain value limits and do neither record the duration and time, nor offer the desirable resolution. The data loggers display the disadvantage of being rather expensive compared to the Transition indicators and, in addition, can be removed easily from the goods to be monitored thus opening the door for manipulation.